<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width:300px;
            height:300px;
            /* background:url(imgs/aaa.jpeg) no-repeat center center; */
            background:url(imgs/xiaogou.jpg) no-repeat center center;
            border:1px solid pink;
            /* background-size:200px 200px; */
            display:none;
        }

        .box2 {
            width:50px;
        height:50px;
        border:1px solid red;
        background:url(imgs/img100.png) no-repeat;
        background-size:50px 50px;
        }

        .box3 {
            width:50px;
        height:50px;
        border:1px solid red;
        background:url(imgs/img50.png) no-repeat;
        background-size:50px 50px;
        }
    </style>
</head>
<body>
    <div class="box"></div>
    <div class="box2">

    </div>
    <div class="box3"></div>
</body>
</html>